Unidirectional flow gear pump



Jim. 11, 1949. a. F. B UNTE 2,453,678

' uummscnoum. FLOW GEAR PUMP Filgd June 2, 1945 IN VEN TOR.

tion.

UNITED STATES PATENT OFFICE UNIDIRECTIONAL FLOW GEAR PUMP George F. Bunte, Detroit, Mich, .assignor to Eaton Manufacturing Company, Cleveland, Ohio,

corporation of Ohio Application June 2, 1945, Serial No. 597,252

4 Claims. (Cl. 1031l7) This invention relates to pumps and more particularly to automatically reversible pumps.

Broadly the invention comprehends the provision of a pump of the rotary type having cooperating internal and external rotors and being so constructed as to be automatically reversible so that regardless ofthe direction 01' rotation, thereof, the pumping will continue in the same direc- An object of the invention is the provision of a highly efiicient, quickly automatically reversible pump.

Another object of the invention is the provision of a pump having pumping means comprising a pair or rotors one within and eccentric to the other automatically reversible upon reverse rotation of the pump by means incorporated in the rotor teeth.

vAnother object of the invention is the provision of an automatically reversible pump having pumping means comprising a pair of rotors one within and eccentric to the other and having inter-engaging teeth forming pumping chambers therebetween, inlet and outlet ports communieating-with such'pumping chambers, said outer rotor being so shiftable in a plane perpendicular to the .axls of rotation of thepump rotors between two limiting positions such that the expanding pumping chambers formed between the teeth of the rotors remain continuously in open communication with the outlet port.

Another object of the invention is the provision of a pump ,constructed as described in the preceding objects having interfering means incorporated in the interengaging teeth for automatically shifting the outer rotor between the limits of its shiitable movement. I

Other objects and advantages of the invention will appear from the following description taken in connection with the drawings forming a part of the specification and in which:

Figure 1 is a vertical sectional view of a pump illustrating the invention; 7

Figure 2 is a transverse sectional view of the pump taken on line 2-4 of Figure 1; I

Figure 3 is a view similar to Figure 2 but showing the rotors in the relative positi'onmthey assume when rotating in a clockwise direction of rotation; and

Figure 4' is an enlarged fragmentary sectional view or the interfering means incorporated in the rotor tooth.

The pump defined by the instant invention is similar in most respects to the pump disclosed in U. 8. Patent No. 2,373,36 issued to Mr. E. S.

. z Witchger with the additional structural feature of incorporating means in the teeth of one 0! the rotors of the pump adapted to engage the teeth of the engaging rotor so as to provide for quick reversal of pump operation upon reverse rotation of the pump shaft. The pump covered by the instant invention has particular relation to that type of pump including a pair of toothed rotors one within and eccentric to the other and having at least one less tooth than the other, theteeth having diametrically opposite full mesh and open mesh positions and preferably remaining in substantially contacting relationship with respect to each other between such positions.

Provision is made for driving one 'ofthe rotors thus causing the other of the rotors through the inner engagement of their respective teeth to be driven thereby and as the inner engaging teeth move away from the full mesh position in the direction oi rotation, they open between them pumping chambers which continue to increase in volume from open mesh position to full mesh position in the direction of rotation.

It has been conventionalpractlce to provide a such rotors in a pump structure .each for rotation about a fixed axis. The pump housing being provided with an inlet port communicating with those pumping chambers increasing in volume and an'outlet port communicating with those pumping chambers decreasing in volume. Inasmuch as each of said rotors has been mounted for rotation about a fixed axis, it will be appreciated that if the direction of rotation of the pump is reversed the pumping chambers of increasing volume are shifted from one side of a medial plane including the full mesh and open mesh positions to theopposite side thereoi; and consequently, the direction of fiow through the pump is correspondingly reversed.

In accordance with the present invention instead oi. mounting the outer rotor for rotation about a fixed axis asin constructions prior to the direction of rotation of the rotors. The pumping force set up between them together with interference means incorporated in either one or the other of the rotors automatically effecting the required movement of the outer rotor thus providing pumping continuously in one direction regardless of the direction of rotation of the pump.

By so employing means providing interference or resistance to sliding or rolling of the teeth of one rotor upon the teethof the other rotor, it is possible to use normal standard porting rather than pinched (restricted, small, under normal size, widely spaced between intake and discharge) porting heretofore. used in reversible pumps of this type. The substitution of standard porting for pinch porting alleviates the condition.

of rapid wear and high stresses previously present in pumps of this nature. Furthermore, by the use of standard ports, the over-all efficiency of the pump is materially increased as compared to pumps using pinch porting.

With particular reference to the drawings, I represents an inner rotor and I2 an outer rotor, the inner being shown as having six teeth I4 and the outer rotor as having seven teeth I6. The rotors I0 and I2 are mounted within a cast housing I8 having a pump chamber 20 opened at one end thereof, said open end of the chamber being normally closed by a cover plate member 22 secured to the housing I8 by any suitable means such as screws 24. I

A shaft 26 rotatably supported in the housing I8 projects through the pumping chamber 22 and has one .end thereof journalled in a suitable bore 28 provided concentrically therewith the cover 22. The inner rotor I6 is fixedly secured on the shaft 26 for rotation therewith of the pumping chamber 2|] by means of a suitable key 30. The rotor II) is preferably of substantially the same axial length as the distance between the bottom 32 of the pumpin chamber 20 and the inner wall of the cover 22, only that amount of axial clearance being provided for the rotor which is necessary for running fit within the housing I8. As shown, relative axial movement between the drive shaft 26 and the inner rotor I0 is prevented by means of snap rings 34, said rings being positioned on either sides of the rotor within circumferential grooves 36 provided in the shaft 26.

The rotor I 2 surrounds the rotor 16 within the chamber 20 and cooperates with the inner wall of cover 22 and the bottom of pump' chamber 20 similarly to the rotor I0. The bearing for rotor I2 is provided by direct contact of the outer surface of the rotor I2 with peripheral wall portions of the pumping chamber 20 although it is well recognized that the rotor could be provided with a separate surrounding bearing'member. The pumping chamber 26 is of materially larger size than the outer rotor I2 so that the rotor may be bodily shifted therein in the plane of its rotation from one position to a relatively different position. As a means for limiting the bodily shifted movement of the outer rotor .I2. the peripheral wall of the pumping chamber 20 has three distinct areas; that is, one extending from a point indicated at A to a point indicated at B another extending from the point A in the op-. .posite direction to a point indicated at B and the third constituting the remainder of the peripheral wall of the chamber 20 and extendin from B to B the latter being generally disposed at a greater distance from the axis of the shaft 26 than the first two surfaces so as to provide ample clearance in the chamber for the shifting of the rotor I2.

.0 and C being equally disposed on diametrically opposite sides of the center of rotation of the inner rotor I6 which as indicated is the axis D of theshaft 26. The distancebetween the center D and each of the centers C and C is equal to the eccentricity of the rotors IO and I2 so that when the outer rotor I2 is lyin in contact with the surface AB or in contact with the surface AB, it is rotatively supported in the proper eccentric relation with respect to the inner rotor I0 in both instances. The surfaces AB and AB not only serve as bearing surfaces for the outer rotor I2 but also serve as stop surfaces which limit bodily shiftable movement of the rotor I2 in either one direction or the other in the plane of its rotation in the chamber 20. It will be understood that in a pump having pumping elements of the type herein described two positions of full mesh and open mesh of the teeth of the pumping elements will be in a plane including the axis of rotation of the inner rotor and the axis of rotation of the outer rotor; that is, the plane is a horizontal plane perpendicular to the plane of the paper including the point D on and the axis of the shaft 26 and including the points C and C Consequently when the rotor I2 is in the position shown in Figure 2, where its axis of rotation is the point C the point of full mesh between the teeth of the rotors will be at the left hand side of the pump in horizontal alignment with the axis of the shaft 26 and the position of open mesh would be at a dimetrically opposite point on the right hand side of the shaft 26. Conversely when the rotors are in the position illustrated in Figure 3, the axis of rotation of the rotor I2 will be the point C under which conditions of the above relation of parts will be reversed; that is, the point of full mesh will lie on the right hand side of the shaft 26 in horizontal alignment with the axis of the shaft 26 and the point of open mesh will lie diametrically opposite from the axis of the shaft 26 therefrom. The pumping action of the pump is ob-- tainable through pumping chambers formed between the respective inner and outer rotors which are opened up or increased in volume as the teeth move from full mesh positionin a direction of rotation of the pumpin element to open mesh position and through contraction or closing of such pumping chambers as the teeth of the two rotors move from open mesh position in the direction of rotation'of the rotors to full mesh position. Thus in the construction shown in the drawing where the outer rotor I2 is in a position indicated in Figure 2 and the rotors are turning in a direction indicated by the arrow, the full mesh position is at the lefthand side of the center D of the shaft 26 of the pumping chambers formed between the teeth l4 and 16 respectively of the rotors I0 and I2 and increasing in volume lie above the axis of the shaft 26, while those decreasing in volume lie below the axis of said shaft.

With referenze to Figure 3 wherein the outer rotor is in a position opposite to that illustrated by Figure 2; the point of full mesh of the pumption of operation of the pump to be in thedirection shown by Figure 2 or Figure 3, the expanding chambers formed between the teeth of the rotors still lie below the axis of the shaft 26 while the contracting chambers formed between the teeth lie above the axis of the shaft 26. Because of this characteristic of. chamber expansion and contraction, the expanding pumping chambers formed betweenthe teeth of the-rotors is always in open communication with an inlet port 38 formed in the inner wall of the housing 18 and port 40 having direct communication with inlet port 38 and providing for delivery of fluid to the opposite side of the rotors from that of port-38. similar] y, the contracting pumping chambers are always in open communication with outlet port 42 formed in the wall of housing l8.

The outer rotor l2 as shown by the drawing has incorporated in one tooth thereof substantially centrally of the tooth, a spring pressed ball 44 held in position whereby normally the ball 44 protrudes a short distance beyond t e crest of the tooth. Although only one ball 4 is shown, it can readily be appreciated that if requirements necessitate a plurality of similar balls 3 may be employed in the other teeth of the rotor and furthermore that the balls might likewise be incorporated in the rotor I rather than in the rotor l2 as here shown. Likewise, any suitable means such as a spring pressed pin or button could be substituted in place of ball 44 for the purpose of serving in an identical capacity. The ball 44 isadapted to be contacted by the tooth engaging portion of rotor. Ill so as to provide in combination with the pressure built up between the teeth of the rotors cooperating to form a contracting pumping chamber means for automatically shifting the outer rotor to the position I illustrated in Figure 2 when the pump is rotating in the direction illustrated in Figure 2; and likel ise, the outer rotor is automatically shifted to the position illustrated in Figure 3 for the same reason whenever the direction of rotation of the pump is reversed from that indicated in Figure 2.

The ball 44; in so being engaged by the teeth of the inner rotor when the pump rotation is reversed acts as interference means normally resisting rotation of the inner rotor sumcient" together with the pumping pressure built up between the teeth to cause the outer rotor to bemoved from one bearing position in chamber 20 to its other position in the chamber. Thus the outer rotor i2 is shifted between its limits of viding chambers in which the fluid being pumped is drawn through the inlet ports 38 and 40 and the fluid delivered between the teeth cooperating to form contracting chambers is delivered into the outlet port 42. eoutlet port 42 are provided respectively with suitable inlet passage 46 communicating with port 38 and aosimilarly suitable discharge passage 48 communicating with the discharge port 42.

It is to be realized that although the interference means spring pressed ball 44) is effective to provide immediate shifting of rotor I2.

from one of its positions to its other position upon reverse rotation of the inner rotor ID, the interference or resistance to sliding of the rotors upon one another during a normal pumping operation is slight and does not materially effect wearing of the inter-engaging parts of the pump rotors; that is, the spring pressed ball moves smoothly across the face of the teeth of the associated rotor with light rolling bearing pressure.

While this invention has been described in-connection with certain specific embodiments, the principle involved is susceptible of numerous other applications that wil1 readily occur to persons skilled in the art. The invention, therefore, is limited only as indicated by the scope of the appended claims.

What I claim is:

1. It pump structure comprising a housing having a chamber therein, pumping means in said chamber comprising inner and outer eccentric rotor members having inter-engaging teeth forming pumping chambers between them, means for supporting and driving one of said rotors about an axis fixed with respect to said housing, said outer rotor beingbodily shiftable in said first mentioned chamber in a plane erpendicular to said axis between two relatively different positions, said housing having inlet and outlet port means opening into said pumping chambers, said ports maintaining the same pumping relation regardless of which of said positions said. outer rotor is in, and resiliently pressed means incorporated in the teeth of one of said rotors adapted to be engaged by the teeth of the other rotor for shifting the outer rotor from one position to another.

shiftable position indicated in Figures 2 and 3 automatically whenever the direction of rotation of the pump is reversed and in accordance with the direction of rotation of the pump. Rotor I2 in so being shifted in the manner described from a position in which its axis of rotation is on one side of the axis of the shaft 2 to a position in which its axis is on the diametrically opposite side is in effect bodily shifted or rotated about the axis of the shaft 26 through an angle of ap- 2. A pump structure comprising a housing having a chamber therein, pumping means in said chamber comprising inner and outer eccentric rotor members having inter-engaging teeth forming pumping chambers between them, means for supporting and driving one of said rotors about an axis fixed with respect to said housing, said outer rotor being bodily sh ftable in said first mentioned chamber in a plane perpendicular, to said axis between two relatively different positions, said housing having inlet and outlet port means opening into said pumping chambers, said ports maintaining the same pumping relation regardless of which of said positions said outer rotor "is in, and spring pressed means incorporated in the outer rotor adapted to be engaged by the inner, rotor upon reverse rotation of the pump so as to effect shifting ofthe outer rotor from one position to a relatively different position,

. 3. A pump structure comprising a housing having a chamber therein, pumping means in said chamber comprising inner and outer eccentric The respective inlet port 38 andouter rotor being bodily shiftable in said first mentioned chamber in a plane perpendicular to said axis between two relatively different positions, said housing having inlet and outlet port means opening into said pumping chambers, said ports maintaining the same pumping relation regardless of which of said positions said outer rotor is in, and a spring pressed ball normally protruding beyond the periphery of the teeth of one of the rotors adapted to be engaged by the teeth of the other rotor for assisting the shifting of the outer rotor from one position to another position immediately upn reverse rotation of the pump.

4. A pump structure comprising a housing having a chamber therein, pumping means in said chamber comprising inner and outer eccentric rotor members having inter-engaging teeth forming pumping chambers between them, means for supporting and driving one of said rotors about an axis fixed with respect to said housing, said outer rotor being bodily shiftable in said first mentioned chamber in a plane perpendicular to said axis between two relatively diflerent positions. said housing having inlet and outlet port means opening into said pumping chambers, said ports maintaining the same pumping relation regardless of which of said positions said outer rotor is in, and a spring pressed ball normally protrudreverse rotation of the pump.

GEORGE F. BUNTE.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,373,368 witchger Apr. 10, 1945 

